Does IL-6 level help in assessment of severity in COVID-19 Pneumonia, and predicting radiological outcome? Tertiary care center experience of 1000 COVID-19 cases in India

Abstract

Introduction: COVID-19 pneumonia is heterogeneous disease with variable effect on lung parenchyma, airways and vasculature leading to long term effects on lung functions. Materials and methods: Multicentric, prospective, observational and interventional study conducted during July 2020 to May 2021, in MIMSR Medical College and Venkatesh Hospital Latur India, included 1000 COVID-19 cases confirmed with RT PCR. All cases were assessed with lung involvement documented and categorized on HRCT thorax, oxygen saturation, inflammatory marker as IL-6 at entry point and follow up. Age, gender, Comorbidity and use BIPAP/NIV and outcome as with or without lung fibrosis as per CT severity were key observations. CT severity scoring done as per universally accepted standard scoring tool as score <7 as mild, 7-14 as moderate and score >15 as severe affection of lung. Statistical analysis is done by using Chi square test. Observations and analysis: In study of 1000 covid-19 pneumonia cases, age (<50 and >50 years) and gender (male versus female) has significant association with IL-6 in predicting severity of covid 19 pneumonia [p<0.00001] & [p<0.010] respectively. CT severity score at entry point with IL-6 level has significant correlation in severity score <8, 8- 15 and >15 documented normal and abnormal IL-6 level as in 190/110, 90/210 and 40/360 respectively. [p<0.00001] IL6 level has significant association with duration of illness i.e., Doi <7 days, 8-15 days and >15 days of onset of symptoms documented normal and abnormal IL-6 levels in 30/310, 160/300 and 130/70 cases respectively. [p<0.00001] Comorbidity as diabetes mellitus, hypertension, COPD, IHD & obesity has significant association in covid-19 cases with normal and abnormal IL-6 level respectively. [p<0.00001] IL-6 level has significant association with oxygen saturation in covid1-19 pneumonia cases; cases with oxygen saturation >90%, 75-90%, and <75% observed as normal and abnormal IL-6 level in 110/100, 150/340 and 60/240 cases respectively [p<0.00001] BIPAP/NIV requirement during course of covid-19 pneumonia in critical care setting has significant association with IL-6 level; cases received BIPAP/NIV during hospitalization were documented normal and abnormal IL-6 level in 155/445, 165/235 cases respectively [p<0.00001] Timing of BIPAP/NIV requirement during course of covid-19 pneumonia in critical care setting has significant association with IL-6 level; cases received BIPAP/NIV at entry point <1 day, 3-7 days and after 7 days of hospitalization were documented significance in four-fold raised IL-6 level in 110/70, 150/160 and 30/80 cases respectively [p<0.00001] Follow-up IL-6 titer during hospitalization as compared to entry point abnormal IL-6 has significant association in postcovid lung fibrosis [p<0.00001] Follow-up IL-6 titer during hospitalization as compared to entry point normal IL-6 has significant association in post-covid lung fibrosis [p<0.00001] Follow-up IL-6 titer during hospitalization as compared to entry point abnormal IL-6 has significant association in predicting cytokine storm irrespective normal or abnormal of IL6 at entry point [p<0.0001] Conclusion: IL-6 is sensitive, reliable, cost effective, and now universally acceptable inflammatory marker in COVID-19 pandemic. IL-6 has very crucial role in covid-19 pneumonia in predicting severity of illness, progression of illness including ‘cytokine storm’ and assessing response to treatment during hospitalization. Follow up IL-6 titer during hospitalization and at discharge can be used as early predictor of post-covid lung fibrosis.